中文摘要：

软键盘被广泛应用于敏感信息输入,但攻击者有可能通过消息截获、控件分析、偷窥、截屏或鼠标记录等方法得到软键盘的输入信息.本文总结和拓展了攻击方法并对相应防御措施进行了探讨;针对键盘布局随机化这一重要防御措施,对现有各方案进行分析;最后设计实现了一种基于细胞自动机的,与输入信息内容和输入过程相关联的软键盘布局随机化方案CAR,实验表明,这一方案具有良好的安全性和可用性.

英文摘要：

Soft keyboard is widely used to input sensitive information. However, attackers can in- tercept the input information of soft keyboard thro by attacks such as messages intercept, compo- nent analysis, peep, screenshots, or mouse record. First, we summarized and improved the exist- ing attacks and corresponding preventive measures. Then we evaluated the existing methods of keyboard layout randomization, which had a major impact on the safety of soft keyboard. Finally, we designed and implemented a layout randomization method based on cellular automata, which exploited the input information and the input process to enhance the randomization of soft key- board layout. Experimental results show that soft keyboards adopted on this method have good performance in both security and availability.